JP7629353B2 - Joint structure - Google Patents

Description

The present invention relates to a joint structure between precast members.

Half-precast members (hereafter referred to as half-PCa members), which integrate the main steel material of a structure with the embedded formwork, are themselves highly rigid, making it possible to omit support work on the underside and sides of the formwork, which is effective in improving productivity when constructing a structure.

When half-PCa components are arranged side by side, the main steel materials of adjacent half-PCa components are generally joined by friction joints or welded joints, but shear reinforcement bars and other components are densely arranged at the joints, making on-site joining work difficult.

In response to this, Patent Document 1 describes a joint structure in which a lap joint is formed in the main steel material in the same manner as a lap joint in rebar, using notches in the precast members, and filling concrete is poured into the joint, making it easy to join precast members together.

Patent No. 6375079

However, in the joint structure described in Patent Document 1, the cross section of the precast member is missing due to the notch, so if loads such as the weight of materials and equipment act on the joint during construction, the precast member may be damaged. In order to prevent damage to the precast member, it is necessary to increase the thickness and strength of the member, but this is costly and uneconomical, and the increased weight of the member reduces workability.

The present invention was made in consideration of the above-mentioned problems, and its purpose is to provide a joint structure between precast members that is easy to install and does not cause damage to the members.

The first invention for achieving the above-mentioned object is a joining structure used when constructing a structure, for joining precast members which have an embedded formwork and a reinforcing material for the structure, wherein a joint material is provided at the end of the embedded formwork of one precast member, the reinforcing material of the precast member is positioned inside the joint material, the reinforcing material protruding from the embedded formwork of the other precast member is positioned inside the joint material, a filling material is filled inside the joint material, the joint material has a bottom plate and a pair of side plates protruding from both sides of the bottom plate, and the reinforcing material is positioned between the pair of side plates of the joint material .
The second invention is a joining structure used when constructing a structure, for joining precast members which have an embedded formwork for the structure and a reinforcing material, characterized in that a joint material is provided at the end of the embedded formwork of one precast member, the reinforcing material of the precast member is disposed inside the joint material, the reinforcing material protruding from the embedded formwork of the other precast member is disposed inside the joint material, a filling material is filled inside the joint material, the joint material is cylindrical, and the reinforcing material is inserted inside the joint material.

In the present invention, a joint is established between the reinforcing materials of one precast member by simply placing the reinforcing material of the other precast member inside the joint material installed at the end of the buried formwork of the other precast member and filling it with filling material, so construction is easy with less on-site work. In addition, because the reinforcing material is placed inside the joint material, there is no need to notch the end of the buried formwork, and there is no risk of damage to the end of the buried formwork.

It is desirable that the joint material be groove-shaped, with a portion of it being embedded in the embedded formwork of one of the precast members and the other portion being open in the normal direction of the embedded formwork.
By embedding a part of the joint material in the buried formwork of one of the precast members, the end of the buried formwork can be reinforced by the joint material, preventing damage to the end of the buried formwork. Also, by forming the joint material into a groove shape and leaving the other part open in the normal direction of the buried formwork, the other precast member can be positioned so that the reinforcing material is inserted into the joint material from the open surface, making on-site work easier. In addition, the filling material has good filling properties, improving the quality of the joint part.

The reinforcing material may be provided with an uneven portion. It is also preferable that the reinforcing material is provided with an end plate.
This improves the adhesion between the reinforcing material and the filler, improving the stress transmission performance of the joint. Also, by providing end plates to the reinforcing material, the fixing force of the reinforcing material to the filler can be increased, preventing it from slipping out of the joint.

The joint material may have an inner surface provided with an uneven portion. It is also preferable that the distance between the pair of side plates becomes smaller from the middle portion of the joint material to the end portion in the component axial direction of the reinforcing material. Furthermore, it is also preferable that an end plate is provided at the end portion of the joint material in the component axial direction of the reinforcing material to prevent the filler from slipping out.
This improves the stress transmission performance of the joint. Also, by providing the joint material with the end plate, it is possible to prevent the concrete inside the joint material from slipping out when a pull-out force acts on the reinforcing material.

It is also preferable that the joint material has a reinforcing portion for reinforcing the side plate against outward bulging.
For example, if a reinforcing material with unevenness on the surface facing the side plate of the joint material is used, when a pull-out force acts on the reinforcing material, the unevenness tries to overcome the filler, generating a force that pushes the filler outward, which may cause the side plate of the joint material to bulge outward. In this way, if there is a risk that the side plate will bulge outward when a pull-out force acts on the reinforcing material, a reinforcing part can be provided in the joint material to prevent the side plate from bulging and ensure stress transmission performance.

It is also desirable that the joint material have a side plate disposed between the multiple reinforcements of one of the precast members, and a side plate disposed on the outside of the multiple reinforcements.
In this case, the side panels between the reinforcing members are subjected to the pushing force of the filler from both sides, and these forces are offset, so that no bulging occurs in the side panels.

The present invention provides a joint structure between precast members that is easy to install and does not cause damage to the members.

A diagram showing a joint structure 10 of a half PCa member 1. A diagram showing a joint structure 10 of a half PCa member 1. A diagram showing the state after concrete C has been poured. FIG. 13 is a diagram showing a modified example of the arrangement of the main steel material 3 and the joint material 4. 4A and 4B are diagrams showing modified cross sections of the joint material 4. FIG. 4 is a diagram showing a modified example of the main steel material 3. FIG. 4 is a diagram showing a modified example of the joint material 4. 4A and 4B are diagrams for explaining the reinforcing portion of the side plate 41 and the joint material 4a.

The following describes in detail a preferred embodiment of the present invention with reference to the drawings.

Figure 1(a) is a diagram showing a joining structure 10 according to an embodiment of the present invention. The joining structure 10 joins half PCa members 1 (1-1, 1-2) arranged side by side in the horizontal direction. Each half PCa member 1 (1-1, 1-2) to be joined is shown in Figure 1(b).

The half PCa member 1 is a precast member used when constructing a structure such as a slab, and comprises an embedded formwork 2 for the structure and a main steel member 3. In addition, a joint member 4 is provided at the end of the embedded formwork 2 of one half PCa member 1-1 of the half PCa members 1 to be joined, on the side of the other half PCa member 1-2.

The embedded formwork 2 is a plate-shaped concrete member, and a structure such as a slab is constructed by pouring concrete C onto the embedded formwork 2 as a bottom formwork.

The main steel material 3 is a reinforcing material for the structure, and is provided on the upper surface of the buried formwork 2. The main steel material 3 is, for example, flat steel, and multiple pieces are arranged in parallel with the plate surface in the vertical direction. Note that the main steel material 3 is not limited to flat steel, and various types of steel materials can be used, including other shaped steel such as H-shaped steel, angle steel, and channel steel.

Of the two ends of the main steel material 3 of one of the half PCa members 1-1 described above, the end located on the side of the other half PCa member 1-2 is placed within the joint material 4. The joint material 4 is provided to correspond to each of the multiple main steel materials 3 of the half PCa member 1-1.

Of the two ends of the main steel material 3 of the other half PCa member 1-2, the end located on the side of one half PCa member 1-1 protrudes from the end face of the half PCa member 1-1 side of the buried formwork 2. This end is arranged within the joint material 4, and within the joint material 4, the main steel materials 3 of both half PCa members 1 are arranged so that their component axial directions are in a straight line.

Figures 2(a) and (b) are diagrams showing cross sections of the buried formwork 2 in the thickness direction of the joint structure 10. Figure 2(a) is a cross section along the component axial direction of the main steel material 3, and Figure 2(b) is a cross section in the direction perpendicular to the axis of the main steel material 3 along line A-A in Figure 2(a). The direction perpendicular to the axis of the main steel material 3 is a direction perpendicular to the component axial direction of the main steel material 3 in a plane. Figure 2(c) is a diagram showing a horizontal cross section of the joint structure 10 at the height of the main steel material 3. Figures 2(a) to (c) show the state before concrete C is poured.

The joint material 4 is a channel-shaped steel material having a side plate 41 and a bottom plate 42, and its cross section is concave. As shown in Figure 2(b), part of the joint material 4 is embedded in the buried formwork 2, and the other part is exposed on the upper surface of the buried formwork 2 and is open in the normal direction of the buried formwork 2 (corresponding to the up-down direction in Figure 2(b)). The joint material 4 is installed so that its axial direction is aligned with the component axial direction of the main steel material 3.

In this embodiment, after one half PCa member 1-1 is installed, the other half PCa member 1-2 is moved from above as shown by arrow a in Figure 1(b), and the end of the main steel material 3 protruding from the half PCa member 1-2 is inserted into the inside of the joint material 4 from the open surface of the joint material 4, and the main steel materials 3 of the half PCa members 1-1 and 1-2 are positioned inside the joint material 4 so that their component axial directions are aligned in a straight line.

At this time, as shown in FIG. 2(a), the end faces of the embedded formwork 2 of the half PCa members 1-1 and 1-2 come into contact with each other, and then concrete C is poured onto the embedded formwork 2 of the half PCa members 1-1 and 1-2 to construct a structure such as a slab.

Figure 3 shows the state after concrete C has been poured in the same cross section as Figure 2(c). In this embodiment, concrete C is also filled inside the joint material 4 as a filler, and a joint portion between the main steel materials 3 of the half PCa members 1-1 and 1-2 is formed inside the joint material 4. When a pull-out force acts on the main steel material 3 in this joint portion, stress (shear stress) is transmitted between the main steel materials 3 via the concrete C and the joint material 4.

In this way, in this embodiment, a joint is established between the main steel materials 3 of both half PCa members 1-1 and 1-2 simply by placing the main steel material 3 of the other half PCa member 1-2 inside the joint material 4 installed at the end of the buried formwork 2 of the other half PCa member 1-1 and filling it with concrete C, so construction is easy with less on-site work. Also, because the main steel material 3 is placed inside the joint material 4, there is no need to notch the end of the buried formwork 2, and there is no risk of damage to the end of the buried formwork 2.

In addition, in this embodiment, by embedding a portion of the joint material 4 in the buried formwork 2, the end of the buried formwork 2 can be reinforced by the joint material 4, and damage to the end of the buried formwork 2 can be prevented. Furthermore, by making the joint material 4 groove-shaped and leaving the other portion open in the normal direction of the buried formwork 2, the half PCa member 1-2 can be positioned so that the main steel material 3 is inserted into the inside of the joint material 4 from the open surface of the joint material 4, making on-site work easier. In addition, the filling properties of the concrete C are also good, which improves the quality of the joint portion.

However, the present invention is not limited to the above embodiment. Below, we will explain modified examples of the joining structure 10 of the present invention, but the configurations described below and the configurations described in the above embodiment can be used in combination as necessary.

For example, in this embodiment, main steel materials 3 such as flat steel bars are provided in the buried formwork 2 as reinforcing materials for the structure, but instead, reinforcing bars or the like may be provided as reinforcing materials. Furthermore, the structure constructed using the half PCa members 1 may be a wall-shaped or column-shaped structure. In this case, it is also possible to arrange the half PCa members 1 side by side in the vertical direction and form joints using joint materials 4 or the like between the main steel materials 3 of the upper and lower half PCa members 1.

In this embodiment, the concrete C is filled inside the joint material 4 when the concrete C of the structure is poured, and there is no need to fill the inside of the joint material 4 with a filler in a separate process, but it is possible to fill the inside of the joint material 4 with a separate filler, and the filler is not limited to concrete. For example, it is also possible to use a cement-based material other than concrete, and it is also possible to use a filler other than a cement-based material. In particular, if the material expands when hardening, the frictional force acting on the main steel material 3 increases as the joint material 4 restrains the expansion pressure, which contributes to the transmission of stress (shear stress). In addition, a filler that can be expected to have adhesive strength with the joint material 4 and the main steel material 3 is also suitable.

In this embodiment, a portion of the joint material 4 is embedded in the embedded formwork 2, but it is also possible to place and fix the joint material 4 on the upper surface of the embedded formwork 2 so that it is not embedded in the embedded formwork 2.

The main steel materials 3 of the half PCa members 1-1 and 1-2 may be placed at any position inside the joint material 4. For example, as shown in FIG. 4(a), they may be placed parallel to one another inside the joint material 4, allowing stress transmission between the main steel materials 3 via concrete C. As shown in FIG. 4(b), the positions of the joint materials 4 in the component axial direction of the main steel material 3 may be changed, and some of the joint materials 4 may be shifted from the other joint materials 4 and placed in a staggered pattern, reducing stress concentration at the joint locations.

The cross-sectional shape of the joint material 4 is not particularly limited, and may be any shape that can accommodate the end of the main steel material 3 inside. For example, the bottom plate 42 of the joint material 4 can be U-shaped as shown in FIG. 5(a) or V-shaped as shown in FIG. 5(b). By making the cross section of the joint material 4 convex downward, bleeding that occurs on the bottom surface of the joint material 4 can be suppressed when the buried formwork 2 is made of concrete. In some cases, the top surface of the joint material 4 may be closed, and the cross section of the joint material 4 may be cylindrical. In this case, however, it is necessary to move the half PCa member 1-2 laterally to insert the main steel material 3 into the joint material 4, which makes construction difficult.

Also, for the main steel material 3, it is possible to provide an uneven portion on the surface facing the side plate 41 of the joint material 4 at the end of the main steel material 3 inserted inside the joint material 4. The uneven portion can be formed by welding a bar such as a reinforcing bar to the surface of the main steel material 3, by groove processing on the surface of the main steel material 3, or by providing a stud 31 as shown in FIG. 6(a), which is an uneven portion, and can improve the adhesion of the concrete C and enhance the stress transmission performance of the joint part. The uneven portion of the main steel material 3 is not limited to this, and for example, a perforated plate 32 can be provided as shown in FIG. 6(b). Also, holes can be provided in the end of the main steel material 3 itself, and the same effect can be obtained. Furthermore, it is possible to provide an end plate 33 at the end of the main steel material 3 as shown in FIG. 6(c), which increases the fixing force of the main steel material 3 to the concrete C, and therefore can prevent the main steel material 3 from coming out of the joint part due to the pulling force acting on the main steel material 3, and can reliably transmit stress between the main steel materials 3.

As shown in FIG. 7(a), the joint material 4 can also have an uneven portion on the inner surface of its side plate 41, which can improve the stress transmission performance of the joint portion as described above. In FIG. 7(a), studs 43 are provided as the uneven portion, but the uneven portion is not particularly limited, and as in the above, uneven portions can be provided by welding rebar to the side plate 41 of the joint material 4 or by performing groove processing instead of the studs 43, or a perforated plate can be provided. Holes can also be provided in the joint material 4 itself.

Furthermore, as shown in FIG. 7(b), the distance between the side plates 41 located on both sides of the main steel material 3 can be made smaller in the axial direction of the main steel material 3 from the middle to the ends of the joint material 4. This makes it easier to transmit the shear stress generated in the concrete C when a pull-out force acts on the main steel material 3 to the side plates 41, and prevents the concrete C from being pulled out of the joint material 4, improving the stress transmission performance of the joint portion.

In addition, as shown in FIG. 7(c), it is also possible to provide end plates 44 at both ends of the joint material 4 in the component axial direction of the main steel material 3. By closing the ends of the joint material 4 with the end plates 44, it is possible to prevent the concrete C inside the joint material 4 from escaping when a pull-out force acts on the main steel material 3, and to ensure stress transmission between the main steel materials 3. The reference numeral 441 denotes a slit provided in the end plate 44 to allow the main steel material 3 to pass through.

In the example of Figures 7(a) to (c), the main steel material 3 is provided with studs 31, but if the main steel material 3 is provided with uneven parts such as studs 31 or end plates 33, when a pull-out force acts on the main steel material 3, the uneven parts of the main steel material 3 will try to overcome the concrete C, generating a force that pushes the concrete C inside the joint material 4 toward the side plate 41, which may cause the side plate 41 of the joint material 4 to bulge outward and impair the stress transmission performance. In this way, if there is a risk that the side plate 41 will bulge outward when a pull-out force acts on the main steel material 3, it is also desirable to provide the joint material 4 with a reinforcing part to reinforce the side plate 41 against outward bulging, which may allow the side plate 41 to be made thinner and reduce costs.

For example, as shown in FIG. 8(a), the side plates 41 of adjacent joint materials 4 can be connected to each other by a connecting plate 45 (reinforcement portion) arranged in a direction perpendicular to the axis of the main steel material 3, thereby reinforcing the side plates 41 of the joint material 4 and preventing the side plates 41 from bulging. Also, as shown in FIG. 8(b), it is possible to arrange triangular reinforcing ribs 46 (reinforcement portion) at the corners of the side plates 41 and the bottom plate 42 and fix the reinforcing ribs 46 to the side plates 41 and the bottom plate 42, which also reinforces the side plates 41 and prevents them from bulging. A similar reinforcing rib 46 can also be provided on the outside of the side plates 41. The shape of the reinforcing rib 46 is not particularly limited.

Furthermore, as shown in FIG. 8(c), it is also possible to connect the side plates 41 of the joint material 4 with connecting members 47 (reinforcements) in a direction perpendicular to the axis of the main steel material 3. The connecting members 47 are, for example, bolts or threaded rebars. By bridging the connecting members 47 between the notches 411 provided in both side plates 41 and tightening nuts from the outside of the side plates 41, the tensile resistance of the connecting members 47 can prevent the side plates 41 from expanding.

As shown in FIG. 8(d), the joint material 4a may have a side plate 41a arranged between adjacent main steel members 3 and a side plate 41b arranged on the outside of the main steel members 3. In this case, the extrusion force of the concrete C described above acts from the main steel members 3 on both sides of the side plate 41a toward the side plate 41a, and these extrusion forces are offset, so that the side plate 41a does not bulge. Although not shown in particular, it is possible to prevent the bulging of the outer side plate 41b by using reinforcing parts such as the reinforcing rib 46 in FIG. 8(b) or the connecting member 47 in FIG. 8(c).

The above describes preferred embodiments of the present invention with reference to the attached drawings, but the present invention is not limited to these examples. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the technical ideas disclosed in this application, and it is understood that these also naturally fall within the technical scope of the present invention.

1, 1-1, 1-2: Half PCa member 2: Buried formwork 3: Main steel material 4, 4a: Joint material 10: Joint structure 31, 43: Stud 32: Perforated plate 33: End plate 41, 41a, 41b: Side plate 42: Bottom plate 44: End plate 45: Connecting plate 46: Reinforcement rib 47: Connecting material

Claims (9)

A joint structure for joining precast members having an embedded formwork and a reinforcing material of a structure, which is used when constructing a structure,
A joint material is provided at an end of the embedded formwork of one precast member, and the reinforcing material of the precast member is disposed inside the joint material;
The reinforcing member protruding from the embedded formwork of the other precast member is disposed inside the joint member;
A filler material is filled inside the joint material ,
A joint structure characterized in that the joint material has a bottom plate and a pair of side plates protruding from both sides of the bottom plate, and the reinforcing material is positioned between the pair of side plates of the joint material . A joint structure for joining precast members having a buried formwork and a reinforcing material of a structure, which is used when constructing a structure,
A joint material is provided at an end of the embedded formwork of one precast member, and the reinforcing material of the precast member is disposed inside the joint material;
The reinforcing member protruding from the embedded formwork of the other precast member is disposed inside the joint member;
A filler material is filled inside the joint material ,
A joint structure characterized in that the joint material is tubular and the reinforcing material is inserted inside the joint material . The joint structure described in claim 1, characterized in that the joint material is groove-shaped, one part of which is embedded in the embedded formwork of one precast member, and the other part is open in the normal direction of the embedded formwork. 4. The joint structure according to claim 1, wherein the reinforcing material is provided with an uneven portion. 5. The joint structure according to claim 1 , wherein the reinforcing material is provided with an end plate. 6. The joint structure according to claim 1 , wherein an inner surface of the joint material is provided with projections and recesses. 4. The joint structure according to claim 1 , wherein the distance between the pair of side plates becomes smaller from the middle portion of the joint material to the end portion in the member axial direction of the reinforcing material. 8. The joint structure according to claim 1 , wherein an end plate is provided at an end of the joint material in the axial direction of the reinforcing material to prevent the filler material from slipping out. 4. The joint structure according to claim 1 , wherein the joint material has a reinforcing portion for reinforcing the side plate against outward bulging.

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